My friends 94 civic had his radiator blow on him the other day. The car is an auto and is completely stock with over 200,000 miles. The car wasn't overheating prior but when he pulled up to a friends house, right before he turned the car off he heard something pop and steam/coolant started to spray out of his radiator. The top portion of the radiator split open.

Replaced the radiator last night but now the car over heats. The top radiator hose gets extremely hot, along with the heater cores hoses leading inside the cabin. But the larger lower hose that is really long stays cool/warm while everything else remains hot.

I've read online that this means the thermostat is bad and needs to be replaced. Does anyone agree and do you think his thermostat suddenly went bad on him and thats what caused the radiator to blow like it did?

I also noticed that his radiator fan does not kick on but the a/c fan does. I've tried searching for a diagram of the radiator relay location but can't seem to find one for his particular vehicle model.

 

How did you add coolant? Did you bleed all of the air out of the system?

The waterpump can only push fluid, not air, so if air is in the system the coolant will not flow correctly.

 

I really dont know too much about hondas and wasnt aware that you had to bleed the system out properly. I read this after we originally replaced the radiator and added coolant to the max.

I just went outside and started the car with the radiator cap off and let it run for a couple of minutes. Temperatures reached normal operating temps but the fluid level did not go down so I couldn't add any more.

Another thing is, since the lower radiator hose is staying cool/warm would this cause the radiator fan's switch that is located by the thermostat think the car was staying cool and not turn the radiator fan on? I turned the a/c on and the fan for the condenser kicks on but the radiator fan never does.

 

checked the volts by the fan and it wasnt getting any voltage, unplugged the coolant temp switch by the thermostat and used a wire to jump the plug and the radiator fan kicked right on. But I'm assuming that the temp sensor isnt working because the coolant isnt circulating so the sensor is reading the cool coolant. Or is the radiator fan suppose to come on with the a/c fan at the same time when the heater/a.c is on inside the car?

 

the fan switch will turn on when the thermostat is open and the lower radiator hose is hot. if the lower radiator hose gets hot and the fan doesnt kick in, the switch,relay, or wire connection is bad.